The goal of this research project is to elucidate the molecular mechanisms controlling eukaryotic mRNA gene transcription by RNA Polymerase II. Defects in mRNA and protein production lead to human disease. A comprehensive knowledge of transcriptional regulatory mechanisms is essentia to truly understand both normal and abnormal processes and ultimately intervene to cure pathological conditions or diseases. The proposed studies will utilize the genetically tractable Bakers Yeast (Saccharomyces cerevisiae) as a model for elucidating the detailed roles that two highly evolutionary conserved transcription factors, TFIID and Motlp, play in the complicated process of mRNA gene transcription by RNA Polymerase II. TFIID is made up of 15 subunits, and the holo-TFIID complex controls the transcription of over 90% of all mRNA encoding genes in both yeast and human cells. Motlp contains two subunits, one shared with TFIID, and the Motlpcomplex controls transcription of 15% of mRNA-encoding genes; many of which are also controlled by TFIID. A multifaceted approach will be utilized that combines biochemical, biophysical, cell biological and genetic methods to examine the interplay of the transcription factors TFIID and Motlp: with DMA, with the DNA-binding regulatory factors that switch mRNA gene transcription on and off, with the RNA polymerase II enzyme that actually synthesizes mRNA and with each other. Successful completion of these experiments will greatly increase understanding of the critical process of mRNA gene transcription, and given that all of these regulatory processes are evolutionary conserved, this work in the yeast model system will provide insights into human mRNA gene transcription mechanisms, and ultimately, human disease.